1. Field of the Invention
This invention relates to conveyor systems of the type having conveying belts trained around rollers to travel in prescribed paths to thereby transport material supported upon the conveying belt between first and second locations and, more particularly, to a load bearing assembly for contacting an unsupported portion of a conveying belt to absorb impact forces and support loads applied thereto. The invention is also directed to a method of assembling the load bearing assembly.
2. Background Art
A wide range of belt conveyor systems are currently being used in many diverse environments. One typical belt conveyor construction has an endless conveying belt which is trained around spaced head and tail pulleys for movement in a prescribed travel path. Material to be conveyed is loaded upon a conveying surface on the conveying belt along a portion of the path in which the conveying belt surface faces upwardly. The advancing conveying belt is capable of transporting material placed thereon from the region adjacent to the tail roller towards the region at which the head roller is located. In the region of the head roller, the transported material discharges, as to be accumulated at that location or transferred to another conveying component. Between the tail and head rollers, materials to be conveyed are placed upon the belt at one or more loading locations. Commonly, the material is dropped onto the conveying belt at the loading location. At the loading location, a suitable belt supporting structure is commonly employed. The supporting structure absorbs downward forces on the conveying belt to avoid excessive belt deformation and absorb impact, as might otherwise potentially damage the conveying belt at the loading location.
Supporting structures as described above have commonly incorporated discrete load bearing assemblies that are referred to as “impact bars.” Designers of impact bars focus on a number of key functional aspects. Impact bars often encounter relatively high loads. If the impact bars are too rigid, applied loads may inflict damage on the conveying belt during loading. Excessive flexing of the impact bars is likewise undesirable in that this condition could likewise result in the infliction of damage to the conveying belt. Additionally, if there is excessive flex of the conveying belt, materials loaded upon the conveying belt may migrate off of the conveying belt and escape around confining skirting at the side boundaries of the conveying belt.
The impact bars must also exhibit good resistance to frictional wear. Under a load, the conveying belt may be continuously borne against the impact bar(s) as the conveying belt travels. Materials used to achieve the desired flexing qualities may not exhibit the required wear resistance. This could lead to frequent repair or reconstruction of the support structure. This repair/reconstruction may require a shut down of the entire conveyor system. As a result, the repair/reconstruction is detrimental not only from the standpoint of the expense directly associated with the repairs, but also from the standpoint of the loss of valuable operating time.
In this vein, it is also a goal of designers of these systems to facilitate the repair/reconstruction of the support structure. Given the severe conditions under which many of these conveyors are operated, regardless of the design of these conveyors, the support structures are prone to wear and failure over potentially a relatively short period of time. Accordingly, the objective of designers is to minimize down time and avoid direct expenses associated with repair/reconstruction of supporting structures.
In order to address the problems, noted above, several different structures have evolved in the industry. U.S. Pat. No. 4,793,470, to Andersson, and U.S. Pat. No. 5,074,407, to Brumby, disclose impact bars made with joined components. One of the components is designed primarily for impact absorption, whereas the other is designed to directly contact the conveying belt and is made from a material that has good resistance to frictional wear.
While the use of two different materials allows the designers to exploit the advantages of each, the industry has encountered problems with marrying different materials such as those used for the impact bars through adhesive or other chemical bonding. There has been a tendency of the joined parts to separate from each other.
Brumby also discloses impact bars which can be individually replaced, as necessary. This avoids the requirement to replace larger portions of the support structure.
Designers of impact bars for the conveying environment, and in other environments, are constantly looking for designs that contribute to more economical construction and repair, yet without sacrificing performance.